1. Field of the Invention
The present invention relates generally to a portable communication device such as a cellular phone or a PDA (Personal Digital Assistant), and in particular, to a portable communication device for minimizing the SAR of electromagnetic waves.
2. Description of the Related Art
A portable communication device generally refers to a portable device like a cellular phone, a PDA, a laptop computer, etc. A mobile station like a cellular phone is a portable terminal that can provide wireless communication services to a user by wirelessly communicating with a base station.
Electronic parts for the portable terminal become smaller and more lightweight along with the present trend of the portable terminal toward high sensitivity and miniaturization. Such portable terminals are classified into a bar type, a flip type, and a folder type according to appearances, or a neck-wearing type and a wrist type according to where they are carried.
Among popular portable terminals, a cellular phone will be taken as an example. FIG. 1 is a perspective view of a conventional cellular phone and FIG. 2 is a partial cut-out sectional view of the interior stack structure of the conventional cellular phone.
Referring to FIG. 1, the cellular phone includes a data input device 104, a data output device 103, an antenna 101, a transmitter 105, a receiver 102, and a battery pack 20, all of which are contained in a body housing 10. A keypad is usually used as the data input device 104 and an LCD (Liquid Crystal Display) module as the data output device 103. A microphone is used as the transmitter 105 and an earpiece including a speaker is used as the receiver 102. The battery pack 20 is composed of a plurality of battery cells (not shown) and generally detachable from the body housing 10 to be recharged when power is used up.
The data input and output devices 104 and 103, the transmitter 105, the receiver 102, and the antenna 101 are installed at appropriate positions of the body housing 10 and the battery pack 20 is detachably installed under the body housing 10.
Referring to FIG. 2, the interior structure of the body housing 10 will be described. Along a vertical direction, the keypad 104 and the LCD module, and the transmitter/receiver are disposed on the top end of the body housing 10 and the battery pack is detachably installed on the bottom end of the body housing 10. A PCB (Printed Circuit Board) assembly PBA1 having circuit parts is located between the keypad 104 and the battery pack 20.
The keypad 104 has a plurality of silicon rubber keys 104a with key tops 104c exposed outward from the body housing 10 to be pressed by a user for data entry. Located on PBA1 are a plurality of button switches 104b that correspond to the plurality of rubber keys 104a. 
This keypad 104 is connected to the PCB assembly PBA1 to input data a user presses on a key top 104c, which depresses rubber key 104a into switch 104b. The battery pack 20 is detachable from the bottom end of the body housing 10. Connection ports (not shown) are separately provided on the bottom end of the body housing 10 and the top end of the battery pack 20. When the battery pack 20 is mounted to the body housing 10, the connection between the connection ports establish a path for supplying power to the body housing 10, particularly the PCB assembly PBA1.
A key frame for the body housing 10 has a plurality of holes for holding the key tops 104c of the keypad 104. This layout results in the emission of electromagnetic waves from the PCB assembly PBA1 through the holes as shown by the arrows on FIG. 2. The electromagnetic waves of the portable terminal eminate from its PCB assembly with a multitude of circuit parts and chips. Those electromagnetic waves have adverse effects on the human body.
In addition, as the portable communication devices become miniaturized by making them thinner, heat emitted from a PCB assembly in a housing is transferred to the head, ear, mouth, or hand of the user, making it inconvenient to converse on the phone.